This disclosure relates to ballistic armor that is designed to protect against ballistic projectiles.
Composite ballistic armor systems, whether for helmets, small arms protective inserts, vehicle armor or structural protective armor, utilize high performance yarns to reduce weight, enhanced ballistic performance, and reduce cost. Traditionally, better ballistic performance has also been achieved through the use of resin-impregnated unidirectional fabrics rather than woven fabrics. These unidirectional (or orthogonal) constructions are typically either a 2-ply 0°/90° configuration, or a 4-ply 0°/90°/0°/90° configuration.
One resin-impregnated unidirectional fabric is a 4-ply construction that, depending on the way it is manufactured, has an overall areal density of 222 grams per square meter (g/m2) up to 520 g/m2. The areal density of the individual unidirectional monolayers used to make the 4-ply construction thus have an areal density of 55.5 g/m2 to 130 g/m2. Assuming a typical resin content, by weight of 12%-17%, each monolayer would have a fiber-only (yarn) areal density of less than 115 g/m2. Forming a monolayer with a fiber-only areal density of less than 112 g/m2 requires yarn spreading, as well as tight control over the spreading, to ensure a consistent fiber web, without voids or gaps between the individual spread yarns, across the product width.